Pneumatic-pressure gauge



A ril 17, 1928. 1,666,787

A. J. -M|CHELIN PNEUMATI G PRES SURE GAUGE Filed March 5. 1927 awucm boa I Patented Apr. 17, 1928.

UNITED STATES PATENT OFFICE.

ANDRE JULES mrcnnnm, or rams, FRANCE, 'assxenoa r incnnnm Er cm, or

CLERMONT-FERRAND, FRANCE, A. CORPORATION OF FRANCE.

rnnumarrc-ranssuan GAUGE.

Applicationfilefl larch 3, 1927, Serial No. 172,36 5, and in Belgium larch 5, 1926 My present invention relates to improvements in pressure gauges, and it is intended to provide a simple and eflicient pressure gauge,lwhich is not apt to get out of order,

- and which rarely needs adjustment, and

which can be quickly and conveniently used when desired, and which may also be read with facility. I

While the invention is especially adaptable for use in registering the pressure of pneumatic tires, it may also be used to register pneumatic or gas pressures of other arrangements or devices than tires, and I do not mean to limit the inveution'to the use neumatic tires onl 1 y invention will understood more clearly after reference to the accompanying drawing, in which The single figure represents a section through the pressure chamber and through the housing containing the operative parts,

parts being broken away.

In the embodiment of the invention shown, the casing A is provided with a pressure chamber A,which is connected by the air duct (1 tothe air chamber 0 which in turn is connected to the tire or other. arrangement (not shown) having the air: or gas whose pressure is to be measured. As

such arrangement is not a part of my pres- This ring U may be kept in place on the casing A in any convenient way, as by swaging out the faces a of the'casing to form with the outer end of the ring a smooth bearing surface to engagethe flanged ends 0' of the elastic sack G, which is made in the form of a glove finger, preferably of soft rubber. Y

These edges of the sack are pressed on firm- 1y by the annular shoulders t of the housing T and thus form an air-tight joint at the sents a hollow cylinder, shown as provided with' two ribs (1 d, which "ribs slidethe piston,

end of the pressure chamber A. D repre-- freely in-the cylindricalportions T and T of the housing T. The spring K projects into the hollow cylinder D- and its outer end surrounds the stem V of the screw plug V. By screwing in or out on this plug,

the compression of the spring K may be 'va-.

ried within limits, and thus the adjustment of the measuring parts of the apparatus may be facilitated. Y

' Mounted in the housing T is a sector W pivoted as at w and having an arm w engaging the rib d on the outer end of the hollow piston D. This sector W is provided with a segmental rack w engaging the pinion X on the shaftX, which carries the pointer or needle X moving over'a dial, not shown. Y represents a coil -'spring, which is so connected to the shaft'X', as to restore the pointer -0r needle to the initial or zero position, as shown in Fig. 2, but will permit the needle -to be swung over the dial as the piston D is pressed outwards wider the action of pneumatic pressure. It will be noted that this piston will press the sector. W in one direction only, and hence will move theneedle over the dial in one direction only and thus it will measure only the maximum pressure, which is admitd to the pressure chamber A. For convenience in reading this pressure, I provide a brake arrangement, which consists of a bent spring Z fastened at one end in the housing as at Z and having its other end bent as at Z to engage the push button Z". This sprmg normally bears on a friction disc w. carried by the shaft w and the ressure of the ring on this friction disc 1s suflicient only to hold the needle against the return movement of the spring Y but will permit the needle to be moved freely under the action of incident to the outward movement of the piston D. Thus, when the sure of the pressure chamber A, this spring Z will hold the needle steady, so it may be conveniently read. V

Now, if the push button Z be pressed on, this will release the spring. Z from engagement with the friction disc'w and there being nothing to hold. the needle, it will be returned totheinitial or zero osition under the action of'the coil spring Obviously, the tension of this coil spring Y may be adjusted in any convenient way, as may also the compression of the spring K.

needle is moved outward to indicate the pres Thus, it will be seen that, the admission of the fluid under pressure to the pressure chamber will cause the piston to move outward and its motion will be transmitted to a needle passing over a dial.

To facilitate reading the dial, I provide a brake, which will hold the needle to ind i-. cate the maximum movement of the cylinder and yet which will permit the needle to be released and returned automatically to the initial position.

Thus, it will be seen that I provide a simple and eflicient device, which is not likely to get out of order ininormal use and which will register accurately the pressure indi. cated and yet which may be conveniently adjusted, when desired.

Having thus described my invention,

what I claim and desire to secure by Letters Patent ofthe United States is:

1. A pressure gauge comprising a pressure chamber provided with an air duct opening'into said cha1nber,'a piston slidable freely in said chamber, a soft rubber sack loosely fitting said piston, and having its outer edges secured to said chamber, the said sack forming a flexible air tight closure for the open end of-said chamber, a balance spring opposing the outward movement of said piston against the pressure of said chamber, said spring having one end bearing on said piston, and the other end bearing on said casing, means for adjusting the compression of said spring, a shaft journalled in said casing with its axis .at right angles to the axis of said piston, an indicator needle push button for releasin mounted on said shaft, a coil spring engaging said shaft and normally return ng Said needle to the zeroposition, and means controlled by said piston for rotating said shaft against the action of said coil spring, with a siring brake normally holding said shaft against rotation by said coil spring, and means for releasing said brake, when desired.

end of said chamber, a balance spring op-'- posing the outward movementof said piston against the pressure of said chamber, said spring having one end bearing on said piston, and the other end bearing on said casing, means .for adjusting the compression of said spring, a shaft journalled in 'said casing with its'axis'at right angles to the axis of said piston, an indicator needle mounted on saidshaft, a coil springengaging said shaft and normally returning said needle toithe zero position, and means controlled by said pi ton fonrotating said shaft against the action of said coil spring, with a spring brake normally holding said shaft against rotation by said coil spring, and a g said brake, when desired.

ANDRE JULES MICHELIN. 

